Switch a light on/off with animation nodes
You can do it animating the light's strength.

(I did it in Cycles)

I couldnt add the screen shots that i took :/


First, select your lamp
Then go to the frame that you want the strength 0
Go to light settings and set the strength to 0
Press the 'i' key with your mouse cursor over the strength value and it will gets yellow
Go to the frame that you want the strength to be 100, set the strength to 100 and press the 'i' key again with the mouse over the number